When I was a kid my dad used to cold smoke most of the fish we caught when camping.
Been a long time since I thought about it, but he used to use a 44 gallon drum (with open top) with an upturned ‘U’ shaped hole in one side at the bottom. Into this he placed the end of a sheet of corrugated iron in the U shape which ran down the slope of the beach. It had sand packed around it to prevent the smoke from escaping and acted as a sort of chimney.
He would light a smouldering sawdust fire at the open end of the corrugated iron chimney and the smoke would drift up the slope, being fairly cool by the time it reached the drum. The drum contained horizontal rods made of high tensile fencing wire, and from this were hung a whole fillet (skin and scales still attached for strength) that had been soaked in brine. The drum was covered in a wet sack to limit smoke loss. Used to light it in the evening and by morning it was done.
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